Effect Of Temperature On Yeast Respiration

Question 1

What type of respiration occurs in yeast?

Answer 1

Anaerobic respiration
(Fermentation)

Question 2

What is the word equation for anaerobic respiration in yeast?

Answer 2

Glucose → Ethanol + Carbon Dioxide
(Releases energy)

Question 3

Name and describe two examples of where yeast is used:

Answer 3

1) Bread
-bubbles created by CO2 causes bread to rise
-the faster respiration takes place, the faster CO2 will be produced, the faster the bread will rise

2) Beer
Ethanol (type of alcohol created by anaerobic respiration of yeast) used in beer

Question 4

What is the effect of temperature on the rate of respiration?

Answer 4

-respiration controlled by enzymes
-enzymes temperature sensitive
-work at optimum temp
-rate of respiration will increase as temperature increases until temperature passes optimum and reaches high temps. where the enzymes will denature → no respiration will then take place (this can be used as a control in experiments)

Question 5

What is the function of the layer of liquid paraffin on top of the yeast and glucose suspension?

Answer 5

Prevents yeast cells from coming in contact with oxygen

Question 6

Why is glucose mixed with yeast?

Answer 6

The glucose enables respiration.

Question 7

When does fresh lime water turn from clear to cloudy?

Answer 7

When carbon dioxide is bubbled through it.

Question 8

What could make experiment 11.2 (pg223) more accurate?

Answer 8

Use a gas syringe to measure the volume of carbon dioxide instead of counting the bubbles in a cylinder with limewater.

Question 9

What is a source of error that could present itself in the results?

Answer 9

The carbon dioxide bubbles are not all the same size, so the collection method is not very accurate.

Question 10

What is hydrogen carbonate solution and what does it do?

Answer 10

It is an indicator solution that changes colour depending on the concentration of carbon dioxide.

Question 11

What colour is hydrogen carbonate solution at normal air levels?

Answer 11

Red

Question 12

What colour does hydrogen carbonate solution turn in the presence of an increase in CO2?

Answer 12

Yellow

Question 13

What colour does hydrogen carbonate solution turn in the presence of a decrease in CO2?

Answer 13

Purple

Question 14

How can you measure respiration?

Answer 14

By how quickly:

1) products form
2) raw materials are used up